This part of the episode really bugged me. Jack rules, but while he might have guessed Lindsey's intentions to harm Sydney, I don't think he could have known how it would be carried out, or assumed that Sloane would cover in the pinch without being overseen by himself or Vaughn. So why the heck he'd take himself completely out of the loop instead of going to save her . . . I mean, really - if we are supposed to assume that Jack's figured out the double-cross, is he really going to trust Sloane over himself?
We know Jack is perfectly willing to get his hands dirty, if necessary, to save Sydney. It just makes no sense to me, save that for some reason, the writers needed to have Sloane be the one to save Syd. And even so, the Jack-Lindsey scene seemed clumsy and awkward. I would've bought it if Lindsey had just decided to temporarily "hold them for further questioning about their whereabouts" to keep them out of things while the exchange took place. They could've tried to escape, and gotten out just in time to see Lindsey fall. This bit was my biggest problem with the episode.
What IS Sloane's endgame? Dang that character for being so intriguing. Arvin's real motivations are of more interest to me than Rambaldi, than Syd's missing years, than the Covenant, than just about anything currently happening on the show. I swear the man seems to be holding all the cards. To borrow a TwoP phrase, "Sensei Sloane," indeed.
As an aside, I didn't see the aforementioned Alice in Wonderland theme in this episode, but then, it was very fast-paced . . . I may have missed something.